CERRO COLORADO MINE

The Cerro Colorado Mine is also known as the Heintzelman Mine.  The Spanish first discovered the silver deposits in the area sometime before 1775. They mined the enriched surface and near-surface silver ores for many years and processed these ores at the Tumacacori Mission using arrastras and primitive adobe furnaces. Between Mexican independence in 1823 and the Gadsen Purchase of 1853, Mexicans periodically worked the mine.  In June1855, a US/Mexico boundary party headed by Lt. Michler found the abandoned mine workings and made reference to them in his report.  In 1856, Major Samuel P. Heintzelman (Commander  of Fort Yuma) with the help of a Mexican guide located the mine and recognized the value of the ore.  Depending on which account you believe He wasted no time in forming the Sonora Exploring and Mining Company with its headquarters in Tubac. Other accounts have Charles Poston forming the company.  However it happened, Heintzelman, who was on furlough from the army, served as the first president of the company and the board of directors included Samuel Colt of Colt revolver fame, Charles Poston who was to become the “Father of Arizona” and Herman Ehrenberg, a cartographer.  Dr. Ruban A. Wilbur who homesteaded the Wilbur Ranch in Arivaca was the company physician.

Mining commenced in 1857 under the supervision of Frederick Brunckow, a German mining engineer.  The first run of ore was processed in adobe furnaces and twelve tons of ore yielded 2,287 ounces of silver and 300 pounds of copper. The bullion was taken on wagons to Guaymas, Mexico where it was shipped to San Francisco.  By 1859, over 100 men were working at the mine.  The main shaft was sunk to 70 feet and was reported to be producing between 300 and 400 ounces of silver per week.  One piece of native silver weighed nearly 900 ounces.  In 1860, a cave-in buried 17 Mexican and Indian miners and their bodies were never recovered.  The peak of production was in 1861 when the main shaft was 120 feet deep and up to 200 workers were processing about 800 ounces of silver per day.

In 1861, the US Army removed its cavalry units from Arizona resulting in the Apaches and Mexican bandits running rampant.  Continuous stealing by mine workers resulted in John Poston, Charles Poston’s brother, taking extreme measures trying to bring the operation under control.  It was estimated that only about half of the silver ended up in company hands.  He caught his foreman, Juanito, stealing silver bullion and executed him as an example to the others.  Instead, some Mexican miners stole what they could and went South to Mexico along with a story that Juanito had buried $70,000 in stolen bullion somewhere near the mine.  Mexican bandits upon hearing the tail, went to the mine and enlisting the support of the remaining Mexican miners, murdered John Poston and two German employees.  John had an aversion to being buried underground and had left instructions that in the event of his death, he would not be buried in the earth.  His remains were placed in a concrete casket above ground, which can be seen along side the dirt road near the mine workings.

Sporadic mining operations continued and in 1869, a new corporation was formed and the mine re-opened but between occasional Indian raids and legal problems, operation continued to be sporadic.  The mine was again reopened in 1878 with plans to bring in the best of machinery.  A post office was opened at Cerro Colorado on 17 April 1879.  The mine remained active until 1899 when a new corporation was formed and a new shaft was sunk, ultimately to a depth of over 550 feet.  Considerable ore was processed between 1900 and 1911. The post office was closed 15 April 1911.  Between 1911 and 1937, the mine was only active sporadically. In 1953, a small flotation mill was built which processed ore from the mine and also from other mines in the area. The mill was removed in the late 1960s and there have been no major operations at the mine since.

The primary metal of interest from the mine was silver but varying amounts of copper, lead zinc and gold were also recovered.

Summary prepared by T. Johnson from various mining articles including “Cerro Colorado Silver Mine, Arizona” by Edgar B. Heyimum, Ph.D.

Additional Material: GVHC Library File 26